• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/77

Click to flip

77 Cards in this Set

  • Front
  • Back
What are muscle spindles?
They consist of 3-10 specialized muscle fibers that are located in skeletal muscles. They provide information regarding the length of a muscle.
What is the result with the activation of the gamma motor system?
Stimulation of the gamma motor system, caused by stretch of the muscle, activates a stretch reflex, which may increase the tone of the involved muscle.
What is a primary?
Sensory receptor cells that conduct action potentials in response to the receptor are called primary receptors. Examples are, free nerve endings, Merkel discs, Pacinian corpuscles, Meissner c. Ruffini end organ, muscle spindle and Golgi tendon organ.
What is a secondary receptor?
Secondary receptors have no axons or have short, axon like projections, and the receptor potentials produced in those cells do not result in action potentials. Instead there is a release of neurotransmitter molecules from the receptor cell that bind to receptors on the membrane of a neuron.
What are Tonic receptors?
Tonic receptors or slowly adapting receptors genertae action potentials as long as a stimulus is applied and adapt slowly. We know where our little finger is at all times without having to look for it.
What is a phasic receptor?
Also known as rapidly adapting receptors, adapt rapidly and are most sensitive to changes in stimuli. This allows us to know again where our little finger is as it moves. We control its movement and know where it will be by our own will.
What are sensory tracts?
The CNS(brainstem) have a number of sensory pathways that transfer information via action potentials from the periphery to various parts of the brain. These are called ascending spinal pathways.
Thermoreceptors in the skin generate action potentials that go along the sensory pathway for pain and temperature. True/False
True. Golgi tendon organs located in tendons generate action potentials that are propagated along the sensory pathways involved with proprioception.
l
(
What three tracts are found in the anterolateral system?
Spinothalmic
Spinoreticular
Spinomesencephalic
What does the spinothalamic tract carry?
It carries pain and temperature in formation, as well as light touch and pressure, tickle and itch sensations.
In the spinothalamic tract, signals pass through a primary, a secondary and tertiary neuron. True/False
True. The primary neuron cell bodies are in the dorsal root ganglia. They relay sensory input from the periphery to the posterior horn of the spinal cord, where they will synapse with interneurons.
What is a secondary neuron?
The primary neurons will synapse with secondary neurons. Axons from these neurons cross to the contralateral or opposite side of the spinal cord through the anterior portion of the gray and white commissures and enter the spinothalamic tract, where they will ascend to the thalamus.
What is the function of the tertiary neurons?
Tertiary neurons from the thalamus project to the somatic sensory cortex.
Some neurons in the spinoreticular tracts do not cross over but ascend on the ipsilateral or same side4 of the spinal cord on which they enter. True/False
True.
What is the spinotectal tract?
A portion of the spinomesencephalic tract, called the spinotectal tract, ends in the superior colliculi of the midbrain and transmits action potentials involved in reflexes that turn the head and eyes toward a point of cutaneous stimulation.
What does the dorsal column/medial lemniscal system carry?
This system carries the sensations of 2 point discrimination, proprioception, pressure and vibration.
Lemniscus means ribbon,
What is the trigeminothalamic tract?
This is made up primarily of afferent fibers from the trigeminal nerve, joined by a few tactile affert fibers from the ear and tongue carried by cranial nerves, V11, 1X and X.
Does the trigeminothalamic tract carry the same information as the spinothalamic tract?
Yes. It carries however, signals from the face, nasal cavity, oral cavity, including the teeth.
What are the sensory areas of the cerebral cortex?
Sensory pathways project to specific regions of the cerebral cortex, referred to as primary sensory areas.
The primary somatic sensory cortex occupies most of the post central gyrus. True/False
True. It is organized topographically relative to the general plan of the body. Sensory impulses conducting input from the feet project to the most superior portion of the primary somatic sensory cortex, and sensory impulses from the face project to the most inferior portion.
The pattern of the primary somatic sensory cortex in each hemisphere is arranged in the form of an upside down half homunculus, that represents the opposite side of the body. True/False
True.
What are upper motor neurons?
These connect to lower motor neurons directly or through interneurons. The cell bodies are located in the cerebral cortex.
What are lower motor neurons/
These have axons that leave the CNS and extend through peripheral nerves to supply skeletal muscles. These are located in the anterior horns of the spinal cord gray matter as well as the cranial nerve nuclei within the brainstem.
When there are disruptions in the signals between the lowest motor neurons and the muscle, the muscles do not work properly; the muscles gradually weaken and may begin wasting away and develop uncontrollable twitching (called fasciculations). When there are disruptions in the signals between the upper motor neurons and the lower motor neurons, the limb muscles develop stiffness (called spasticity), movements become slow and effortful, and tendon reflexes such as knee and ankle jerks become overactive. Over time, the ability to control voluntary movement can be lost. True/False
True.
Motor pathways from the primary motor cortex control many voluntary movements, especially fine motor movements of the hands. True/False
True. This region is located on the precentral gyrus. Only app. 30% of UMN are located in the primary motor cortex. Another 30% are in the premotor area and the rest are in the primary somatic sensory cortex.
Are motor tracts descending pathwyas?
Yes.They are descending pathways containing axons that carry action poptentials from regions of the cerebrum or cerebellum to the brainstem or spinal cord.
Is the descending motor fibers divided into 2 or 3 groups?
It is divided into 2 groups. The direct and indirect pathway.
The direct also called the pyramidal are involved in maintaining muscle tone and controlling the speed and precision of skilled movements(dexterity).
Indirect pathways or extrapyramidal are involved in less precise control of motor functions, such as body coordination and cerebellar function.
Why is the term "direct pathway" used?
Because UMN in the cerebral cortex, whose axons form these pathways synapse directly with LMN in the brainstem or spinal cord. They are called "pyramidal" because the fibers of these pathways from the medullary pyramids.
What are the 2 tracts in the direct pathway system?
Cortcospinal(movements below the head)
Corticobulbar(movements of head and neck)
What is brown Sequard syndrome?
This is a lesion of the spinal cord that destroys half the cord at a specific level?
What are some symptoms of B-S syndrome?
There is a contralateral loss of pain and temperature because fibers entering the anterolateral system cross over where they enter the spinal cord and ipsilateral loss of proprioception, two point discrimination, and most upper motor control.
Where do neurons of the rubrospinal tract begin?
They begin in the red nucleus, which is located in the boundary between the diencephalon and the midbrain.
From where does the red nucleus receive input?
From both the motor cortex and the cerebellum.
Lesions in the red nucleus result in intention tremors, similar to those observed in cerebellar lesions.
From where do the vestibulospinal tracts originate?
From the vestibular nuclei. They descend in the anterior column and synapse with interneurons and lower motor neurons in the ventromedial portion of the spinal cord central gray matter.
What do vestibulospinal tract fibers influence?
They influence neurons innervating extensor muscles in the trunk and the proximal portion of the lower limbs. They are important for maintaining upright posture and balance on one leg.
Neuron cell bodies of the reticulospinal tract are in the reticular formation of the pons and medulla oblongata. True/ False
True. This tract maintains posture and balance on one leg as a result of the cross extensor reflex. It enhances the function of alpha motor neurons.
Where does the tectospinal tract originate from?
From the superior colliculus (tectum or roof) of the mesencephalon.
It controls reflex movement to bright lights, noises and rapid movements.
Why are the basal nuclei important?
They are important in planning, organizing and coordinating motor movements and posture. These circuits link the basal nuclei with each other with the thalamus and the cerebral cortex.
What is the spinocerebellum?
The vermis and medial portion of the lateral hemisphere are jointly referred to as the spinocerebellum. It helps to accomplish fine motor coordination of simple movements by means of its comparator function.
What is a comparator?
It is a sensing device that compares the data from 2 sources, in this case, the motor cortex and peripheral structures. Touching ones nose would be an example.
How is Parkinson's disease symptomatically characterized?
Muscular rigidity, loss of facial expression, tremors, a slow shuffling gait, and sometimes lack of movement. A resting tremor such as pill rolling is quite a common early sign of a potentially progressing disease.
What causes the increased rigidity in Parkinson's disease?
It results from defective inhibition of some of the basal nuclei by the substantia nigra, one of the basal nuclei in the midbrain.
It is caused by the death of dopamine containing neurons in the substantia nigra.
Dopamine is an inhibitory neurotransmitter that modulates motor activity. True/False
True.
How can Dopamine be treated?
It is typically treated with levodopa, which is a precursor to dopamine, or with Sinemet, which is a combination od L-dopa and carbidopa.
What is carbidopa/
It is a decarboxylase inhibitor that prevents L-dopa from breaking down before it can reach the brain.
Dyskinesias are occasionally a side effect of levodopa.
Ropinirol and pramipexole are other drugs under investigational use.
What is glial cell line derived neurotrophic factor?
GDNF is a protein that enhances the survival of dopamine secreting neurons.
Chronic stimulation of the globus pallidus(lentifom) with an electrical pulse generator has shown some promise. True/false
True. Stem cell transplantation is as well under investigation.
Amyotrophic lateral sclerosis usually affects people between the ages of 40 and 70. True/False
True. About 10% of the ALS cases are inherited.
How does ALS begin?
It begins with weakness and clumsiness and progresses within 2-5 years to loss of muscle control as both UMN and LMN are selectively destroyed.
What is one of the suspected causes of noninherited ALS?
It is unknown. The inherited cause is from a mutation in DNA coding for the enzyme superoxide dismutase(SOD). This eliminates the free radical superoxide from the body.
What does SOD catalyze?
It catalyzes the conversion of superoxide to H2O2 which is then converted by catalase to O2 and H2O. If SOD is defective, then superoxides cannot be degraded. Motor neurons are particularly susceptible.
What is the Wernicke area necessary for?
For understanding and formulating coherent speech.
The Broca area initiates the complex series of movements necessary for speech.
What is the name of th bundle of neurons that connect Broca's and Wernicke's area?
Arcuate Fasciculus.
What is Aphasia?
This is absent or defective speech due to lesions in the Broca or Wernicke regions.
What are the 4 types of aphasia?
1. Receptive-(Wernicke) Defective auditory and visual comprehension comprehension of language, and defective naming of objects.
2. Anomic- results in fluent but circular speech from poor word finding ability.
3. Conductive- Poor repetition with good comprehension.
4. Expressive-(Broca) hesitant and distorted speech,
There is also a "Jargon" aphasia, where the patient speaks fluently but unintelligibly.
The formation of short term memory involves the enhancement of synaptic activity by long term potentiation. True/False
True. This mechanism facilitaes or potentiates the future transmission of action potentials.
What is there an increase of in long term potentiation?
There is either an increase in the number of vesicles containing the neurotransmitter glutamate released on the presynaptic side or an increase in the number of glutamate receptors on the postsynaptic side.
Is calcium involved in long term potentiation?
Yes. It involves the activation of protein kinases by calcium. Ca+2 enters the post-synaptic terminal via glutamate receptors and binds to protein calmodulin.
What is calmodulin dependent protein kinase 2?
The Ca+2 -Calmodulin complex activates CDPK-2 which both phosphorylates glutamate receptors to increase their activity and sends signals to move additional glutamate receptors from internal vesicles to the post-synaptic memebrane.
Long term memory are stabilized by the formation of additional synaptic connections following new protein syntheisi. True/False
True. They are more resistant to disruption.
Short term memeory to long term memory is referred to as "consolidation".
Regarding consolidation, what is involved in the protein syntesis?
The synthesis of new proteins that increase the number and size of synaptic contacts along with increased synaptic transmission of long term potentiation.
What is CREB?
Genes that encode proteins involved in synapse formation are turned on by cAMP and Ca+2 signaling pathways. A cAMP responsive transcription factor called CREB is particularly important for activating gene transcription.
What do these newly synthesized proteins include?
They include cytoskeletal proteins that create small protrusions from dendrites called dendritic spines. new synapses are then formed on dendritic spines. There is an increased number of strengthened synapses.
Alzheimer's disease involves a general decrease in brain size, resulting from loss of neurons in the cerebral cortex.True/False
True>
Alzheimer's disease involves a general decrase in brain size resulting from a loss of neurons in the cerebral cortex. True/False
True. The gyri become narrower and the sulci widen.
What is Alzheimer's disease pathologically described as?
It is characterized by the appearance of amyloid plaques and neurofibrillary tangles.
What exactly are amyloid plaques/
They are localized axonal enlargements of degenerating nerve fibers, containing large amounts of beta amyloid protein.
What are neurofibrillary tangles?
These are filaments inside the cell bodies of dead or dying neurons.
Chromosome 19 appears to be the most involved for the late set form.
What is apolipoprotein E?
This protein binds to beta amyloid protein and is known to transport cholesterol in the blood. This has been associated with Alzheimer's disease.
ApoE-111 is the normal protein whereas apoE-1V is an abnormal mutant form that has been found in amyloid plaques and neurofibrillary tangles.
People with 2 copies of the apoE-1V gene are 8 times more likely to develop the disease than people with 2 copies of the apoE-111 gene. True/False
True. This is because the apoE1V binds to beta amyloid more rapidly and more tightly than apoE-111 does.
What is the tau protein?
Apoe may be involved in regulating phosphorylation of tau which is involved in microtubule formation inside neurons. If tau is over phosphorylated, the microtubules are not properly constructed and the tau proteins intertwine to form neurofibrillary tangles.
Neurons contain specialized membrane lipids known as_________________.
Gangliosides.
Are gangliosides broken down?
Yes. Lysosomes contain a variety of hydrolytic enzymes including those that digest gangliosides.
Hexosaminidase is one lysosomal enzyme. Hexosaminidase A breaks down a specific type of ganglioside called GM2 ganglioside.
What is the gene called that encodes hexosaminidase A?
It is called Hex-A and is found on chromosome 15.
What is Tay Sachs disease?
It is an autosomal recessive lysosomal enzyme disorder caused by mutations in the hex-A gene. Gangliosides accumulate in cells and damages them, especially in the CNS.
Hex-A also breaks down gangliosides in the light sensitive cells in the eye. True/False
True. Blindness can result.